Pressure load compressor diffuser

ABSTRACT

The present invention relates to a turbocharger compressor diffuser loading plate that is in contact with a vaned diffuser and that is in communication with the compressor volute. The diffuser loading plate is pressure loaded so that it moves axially in response to pressure thereby maintaining an effective seal of the open side of the vaned diffuser. The present invention minimizes a loss in compressor performance caused by movement of the compressor housing.

CROSS-REFERENCES TO RELATED APPLICATIONS

Not Applicable.

BACKGROUND OF THE INVENTION

1 Field of the Invention (Technical Field)

The present invention relates to turbocharger compressor vaned diffusers, specifically to a diffuser plate that is axially movable in response to pressure from the compressor housing volute so that, as the compressor housing moves, an effective seal is maintained on the open side of the compressor's vaned diffuser.

2. Description of Related Art

Note that where the following discussion refers to a number of publications by author(s) and year of publication, because of recent publication dates certain publications are not to be considered as prior art vis-a-vis the present invention. Discussion of such publications herein is given for more complete background and is not to be construed as an admission that such publications are prior art for patentability determination purposes.

Turbochargers for pressurizing or boosting the intake air stream into an internal combustion engine include an exhaust gas turbine through which the engine's exhaust gas is routed so that the exhaust gas turbine spins within the turbocharger housing. The exhaust gas turbine is connected via a shaft to a radial air compressor impeller disposed within the compressor housing so that as the exhaust gas turbine turns, the compressor impeller also turns within the compressor housing and causes intake air to axially enter the compressor housing, go past the impeller, then change direction past a diffuser before entering a compressor housing volute. After the intake air is pressurized or boosted, it exits the turbocharger to be mixed with fuel then sent to the engine combustion chamber.

The diffuser in the compressor housing can either be part of the compressor housing or it can be a separate component attached within the compressor housing. By slowing down the air that is taken into the compressor housing, the diffuser converts the velocity energy to pressure energy and produces air boost pressure in the turbocharger. The diffuser can include one or more vanes that project outwardly from the diffuser surface and that extend in a generally radial direction in line with the direction of air flow coming from the compressor impeller. The vanes force the air leaving the compressor impeller to flow in a particular direction, reducing air flow velocity in a way that favors a particular application demand such as a particular engine speed or torque requirement. Thus, turbocharger compressors use vaned diffusers to increase compressor stage efficiency.

Vane diffusers include those constructed as a separate component of the compressor housing and that are shaped in the form of an annular ring designed to fit against a backplate axial wall surface. Typically, at least one pin is placed axially between the vane diffuser and the backplate to prevent the vane diffuser from rotating within the compressor hosing.

Typically, vaned diffusers are open sided and take advantage of either the backplate or compressor housing to form the sealing side of the diffuser. However, as compressor outlet pressures are increased, the compressor housing tends to move, and the clamp load that clamps the diffuser against the back plate is decreased thereby impacting the effectiveness of the diffuser seal and resulting in leakage around the diffuser. The loss of sealing effectiveness and the resulting leakage causes a significant loss of compressor efficiency.

Also typical in the prior art is an elastomeric O-ring that is interposed, for example, between the vane diffuser and the backplate to both provide an air leakage seal and to pressure load the vane diffuser away from the backplate. This pressure loading is used to urge the vane diffuser away from the backplate as the compressor housing moves axially away from the backplate during operation. Therefore, pressure loading is intended to keep the vane diffuser in contact with the housing during such axial movement to prevent compressor performance losses caused by air flow restrictions between the compressor housing and the vane diffuser. However, the O-ring energizer cannot provide both the range and consistent degree of pressure loading that is required because the ring force provided by the O-ring energizer decreases rapidly as the vane diffuser is moved away from the backplate (thus effective for only a very limited range of motion), and the known elastomers are known to degrade and creep at high compressor operating temperatures so that the energizer spring rate decreases over time.

Another approach to ensure that the vane diffuser remains in contact with the compressor housing as the compressor housing moves during compressor operation is provided by U.S. Pat. No. 6,168,375 wherein the vaned diffuser is spring-loaded.

Other approaches to ensure for an effective seal of the vane diffuser are desirable, particularly those that involve simple components having few or no moveable parts.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a movable diffuser loading plate to provide a sealing surface against the open side of a compressor vaned diffuser. Thus, an embodiment of the present invention provides a turbocharger compressor comprising a housing having a volute, a backplate attached to an exterior surface of the housing, an impeller rotatably mounted within the housing, an annular vaned diffuser disposed in the housing between the volute and the impeller, said vaned diffuser axially facing an axially facing surface of said backplate, and a diffuser loading plate adjacent to the vaned diffuser, said loading plate in communication with the volute via a pressure port, and said diffuser loading plate moveable in response to pressure from the volute so that the diffuser loading plate imposes an axially directed pressure load to provide a seal on an open end of the vaned diffuser.

The compressor further comprises a pressure loading cavity adjacent to the diffuser loading plate and in fluid communication with the pressure port.

In an embodiment, the vaned diffuser and the diffuser loading plate are integral.

In an embodiment, the vaned diffuser is located between the back plate and the diffuser loading plate. In an alternative embodiment, the diffuser loading plate is located between the backplate and the vaned diffuser.

The diffuser loading plate may comprise a disc.

Another embodiment provides a compressor diffuser assembly for placement in a fluid passageway between a compressor impeller and a compressor volute, said assembly comprising an annular vaned diffuser adapted to be placed between the volute and the impeller so that the vaned diffuser axially faces an axially facing surface of a compressor backplate, a diffuser loading plate adjacent to the vaned diffuser, and a pressure port in communication with the volute and the diffuser loading plate, said diffuser loading plate moveable in response to pressure from the volute so that the diffuser loading plate imposes an axially directed pressure load to provide a seal on an open end of the vaned diffuser. The assembly preferably further comprises a pressure loading cavity adjacent the diffuser loading plate and in communication with the pressure port.

In an embodiment, the vaned diffuser and the diffuser loading plate are integral.

The diffuser loading plate preferably comprises a disc.

Still another embodiment provides a vaned diffuser assembly for use in a turbocharger compressor, said assembly comprising a diffuser loading plate in contact with a vaned diffuser, and said assembly positionable between a housing and a backplate of the compressor. The diffuser loading plate and the vaned diffuser may be integral.

Other objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings, which are incorporated into, and form a part of, the specification, illustrate one or more embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating one or more preferred embodiments of the invention and are not to be construed as limiting the invention. In the drawings:

FIG. 1 is a cross section view of a turbocharger of an embodiment of the present invention;

FIG. 2 is a close-up cross section of the compressor of the embodiment of FIG. 1 wherein the vaned diffuser is located at the backplate; and

FIG. 3 is a close-up cross section view of the compressor wherein the vaned diffuser is located at the housing.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a movable compressor diffuser loading plate. The diffuser loading plate may be integral with a vaned compressor diffuser so that the diffuser loading plate loads the diffuser against the backplate or against the compressor housing. Alternatively, the diffuser loading plate and the diffuser may be non-integral so that the diffuser loading plate provides a sealing surface against the open side of a vaned diffuser. In any of these embodiments, the diffuser loading plate communicates with the compressor outlet pressure via a pressure port. The diffuser loading plate is free to move within the compressor stage assembly. As the compressor outlet pressure increases, the pressure exerted against the diffuser loading plate increases thus providing the necessary load to provide a seal at the open side of the diffuser. Even if the compressor housing moves, the pressure loading maintains the sealing of the diffuser.

As used in the specification and claims herein, the terms “a”, “an”, and “the” mean one or more.

Turning now to the figures, which describe a non-limiting embodiment of the present invention that is illustrative of the various embodiments within the scope of the present invention, FIG. 1 shows a cross-section of turbocharger 200 with exhaust gas turbine 210 linked to impeller 110 within compressor assembly 100. Compressor assembly 100 is shown with housing 102 connected to backplate 106. Impeller 110 is located within compressor assembly 100 and sends intake air into housing volute 104. Intake air is slowed down by diffuser 120 which is disposed between housing 102 and backplate 106, is shown as being annular, and axially faces an axially facing surface of backplate 106. Diffuser 120 is a vaned diffuser, and is shown having vanes 121. Diffuser loading plate 130 is shown disposed between housing 102 and diffuser 120.

FIG. 2 shows a close-up of the embodiment of FIG. 1. In this embodiment, diffuser loading plate 130 is shown as being integral with diffuser 120. Diffuser loading plate is disposed between vaned diffuser 120 and pressure loading cavity 140 and in communication with pressure port 142. Diffuser loading plate 130 preferably comprises a disc that is free to axially move or “float” within compressor assembly 100 (although other geometries or shapes are applicable and available to the construction and design of loading plate 130). Thus, movable diffuser loading plate 130 is loaded via air pressure to load diffuser 120 against backplate 106.

In another embodiment, shown in FIG. 3, the orientation of diffuser loading plate 130 and diffuser 120 is reversed so that diffuser 120 is adjacent housing 102, and diffuser loading plate 130 is located between diffuser 120 and backplate 106. In that embodiment, pressure loading cavity 140 and pressure port 142 are located in backplate 106.

As noted above, utilizing the same principles wherein diffuser loading plate 130 can move within compressor assembly 100, and as easily visualized referring to FIG. 2, another embodiment does not integrate diffuser loading plate 130 with diffuser 120. Thus, diffuser 120 is located at backplate 106, and diffuser loading plate 130 is loaded via air pressure toward diffuser 121 to seal any gap that might otherwise exist between vanes 121 and diffuser loading plate 130.

In yet another embodiment using the principles described above and wherein diffuser loading plate 130 and diffuser 120 are not integral, and as easily visualized referring to FIG. 3, diffuser 120 is connected to housing 102. Diffuser loading plate is located adjacent backplate 106 between diffuser 120 and backplate 106. Thus, pressure cavity 140 and pressure port 142 are disposed at backplate 106. Again, pressure loaded diffuser loading plate moves axially against diffuser 120 to provide effective sealing.

In all embodiments, as compressor outlet pressure is increased (and compressor housing 102 moves axially away from backplate 106) pressure is increased on diffuser loading plate 130 to maintain contact/sealing of an open side of diffuser 120 thus maintaining high compressor efficiency.

It is also understood that pressure cavity 140 may be comprise a continuous, generally annular cavity, or may comprise open sections arranged in an annular configuration. The geometry and orientation of cavity 140 may vary as understood by those skilled in the art. Pressure port 142 may likewise vary in orientation, geometry, etc.

It is also understood that in other embodiments, loading other than pneumatic loading, such as, but not limited to, mechanical loading of diffuser loading plate 130, may be utilized.

The compressor housing, vaned diffuser, and backplate, in accordance with the present invention, are attached together according to conventional practice and are combined with other parts conventionally associated with turbochargers to provide a turbocharger for internal combustion engines that incorporates the pressure loaded compressor diffuser of the present invention. Thus, the present invention provides for the axial movement of an integrated diffuser loading plate/vaned diffuser combination and, alternatively, for the axial movement of a diffuser loading plate that is not integral to the diffuser. In all embodiments/applications, an effective seal of the open side of a diffuser is maintained to thereby maintain a smooth air flow transition with the compressor housing such that improved compressor performance is provided.

The preceding examples can be repeated with similar success by substituting the generically or specifically described components, mechanisms, materials, and/or operating conditions of this invention for those used in the preceding examples.

Although the invention has been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above are hereby incorporated by reference. 

1. A turbocharger compressor comprising: a housing having a volute; a backplate attached to an exterior surface of said housing; an impeller rotatably mounted within said housing; an annular vaned diffuser disposed in said housing between said volute and said impeller, said vaned diffuser axially facing an axially facing surface of said backplate; and a diffuser loading plate adjacent to said vaned diffuser, said loading plate in communication with said volute via a pressure port, and said diffuser loading plate moveable in response to pressure from said volute so that said diffuser loading plate imposes an axially directed pressure load to provide a seal on an open end of said vaned diffuser.
 2. The compressor of claim 1 further comprising a pressure loading cavity adjacent to said diffuser loading plate and in fluid communication with said pressure port.
 3. The compressor of claim 1 wherein said vaned diffuser and said diffuser loading plate are integral.
 4. The compressor of claim 1 wherein said vaned diffuser is located between said backplate and said diffuser loading plate.
 5. The compressor of claim 1 wherein said diffuser loading plate is located between said backplate and said vaned diffuser.
 6. The compressor of claim 1 wherein said diffuser loading plate comprises a disc.
 7. A compressor diffuser assembly for placement in a fluid passageway between a compressor impeller and a compressor volute, said assembly comprising: an annular vaned diffuser adapted to be placed between the volute and the impeller so that said vaned diffuser axially faces an axially facing surface of a compressor backplate; a diffuser loading plate adjacent to said vaned diffuser; and a pressure port in communication with said volute and said diffuser loading plate; said diffuser loading plate moveable in response to pressure from said volute so that said diffuser loading plate imposes an axially directed pressure load to provide a seal on an open end of said vaned diffuser.
 8. The assembly of claim 7 further comprising a pressure loading cavity adjacent to said diffuser loading plate and in fluid communication with said pressure port
 9. The assembly of claim 7 wherein said vaned diffuser and said diffuser loading plate are integral.
 10. The assembly of claim 7 wherein said diffuser loading plate comprises a disc.
 11. A vaned diffuser assembly for use in a turbocharger compressor, said assembly comprising a diffuser loading plate in contact with a vaned diffuser, and said assembly positionable between a housing and a backplate of the compressor.
 12. The assembly of claim 11 wherein said diffuser loading plate and said vaned diffuser are integral. 